Independent Submission B. Berry, Ed.
Request for Comments: 5578 S. Ratliff
Obsoletes: 4938 E. Paradise
Category: Informational Cisco
ISSN: 2070-1721 T. Kaiser
Harris Corporation
M. Adams
L3 Communications
February 2010
PPP over Ethernet (PPPoE) Extensions for Credit Flow and Link Metrics
Abstract
This document extends the Point-to-Point Protocol over Ethernet
(PPPoE) with an optional credit-based flow control mechanism and an
optional Link Quality Metric report. These optional extensions
improve the performance of PPPoE over media with variable bandwidth
and limited buffering, such as mobile point-to-point radio links.
Status of This Memo
This document is not an Internet Standards Track specification; it is
published for informational purposes.
This is a contribution to the RFC Series, independently of any other
RFC stream. The RFC Editor has chosen to publish this document at
its discretion and makes no statement about its value for
implementation or deployment. Documents approved for publication by
the RFC Editor are not a candidate for any level of Internet
Standard; see Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc5578.
IESG Note
The PPP Extensions Working Group (PPPEXT) has reservations about the
desirability of the feature described in this document. In
particular, it solves a general problem at an inappropriate layer and
it may have unpredictable interactions with higher and lower level
protocols. The techniques described in this document are intended
for use with a particular deployment technique that uses a PPP
termination separated from a radio termination by an Ethernet, and
that has radio-side flow control for a slower PPP-only link to remote
Berry, et al. Informational [Page 1]RFC 5578 PPPoE with Credit Flow and Metrics February 2010
nodes. Implementors are better advised to avoid split termination
with inter-media protocol translation, and use standard Internet
Protocol routing instead.
Copyright Notice
Copyright (c) 2010 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http:trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document.
Table of Contents
1. Introduction ....................................................3
2. Terminology .....................................................4
3. Overview of Protocol Extensions .................................5
3.1. TLVs .......................................................5
3.1.1. Credits TLV .........................................5
3.1.2. Metrics TLV .........................................6
3.1.3. Sequence Number TLV .................................7
3.1.4. Credit Scale Factor TLV .............................8
3.2. Discovery Stage Extensions .................................8
3.2.1. PPPoE Active Discovery Request (PADR) ...............9
3.2.2. PPPoE Active Discovery Session-Confirmation
(PADS) .............................................11
3.2.3. PPPoE Active Discovery Session-Grant (PADG) ........13
3.2.4. PPPoE Active Discovery Session-Credit
Response (PADC) ....................................15
3.2.5. PPPoE Active Discovery Quality (PADQ) ..............16
3.3. PPP Session Stage Extensions ..............................18
4. Credit Flow Considerations .....................................19
5. PADG and PADC Retransmission ...................................20
6. Other Considerations ...........................................20
7. IANA Considerations ............................................21
8. Security Considerations ........................................21
9. References .....................................................21
9.1. Normative References ......................................21
9.2. Informative References ....................................21
Appendix A. Examples of Session Credit Flows ......................22